Most common type of space junk

The most common type of space junk is known as "fragmentation debris", or the remnants on on-orbit explosions and collisions (also known as "breakup events"). According to figures published by the NASA Orbital Debris Program Office in 2018, fragmentation debris represents 52.6% of all tracked objects in Earth orbit.

As of 31 Dec 2020, there have been 566 documented "on-orbit fragmentation events" (satellites or rocket bodies exploding in space). There are about 12 of these events every year. Most commonly, they are caused by the propulsion systems (explosions of left-over fuel) but intentional destruction (anti-satellite weapon tests) and unintentional collisions also play a role.